As the electronics industry continues to evolve, the density of electronic devices continues to increase. That is, more and more circuits are being included on integrated circuit devices without a corresponding increase in device size. Such integrated circuit devices generate substantial amounts of heat during operation. Thus, due to increases in circuit density, integrated circuit devices are requiring corresponding increases in heat dissipation to ensure device performance and system reliability.
For example, a copper heat sink may be mechanically clamped down on a microprocessor chip of an integrated circuit (IC) device. The heat sink may be directly or remotely cooled. To ensure better heat transfer from the microprocessor chip to the heat sink, a thermally conductive interface layer has traditionally been applied. Traditional thermally conductive interface layers have included polymer greases and gels, and metal reflow solders.
Polymer greases and gels suffer from a limitation of low thermal conductivity. Additionally, such polymers degrade with temperature and thermal cycling which results in diminished properties during the operating life. Metal reflow solders entail relatively difficult manufacturing and rework processes adding cost.
More advanced interface materials used to overcome some of above-described shortcomings of traditional thermally conductive interface layers include phase-change materials (PCMs) and low melting alloys (LMAs). PCMs are typically stable in an interface between an integrated circuit device and a heat sink, but are thicker than other polymer materials. This thickness results in poor thermal performance. LMAs provide superior thermal conductivity by forming continuous liquid metal films in an interface between an integrated circuit device and a heat sink at operating temperatures. However, oxidation products of all suitable LMAs degrade performance in service.
Metal foils have previously been tested for use as thermal interface materials, but such foils have not performed reliably in this application. Specifically, metal foils have not conformed well enough to surface irregularities and deviations from co-planarity, thereby resulting in unacceptable temperature distributions on integrated circuit devices.
In view of the foregoing, it would be desirable to provide a technique for increasing heat dissipation from integrated circuit devices which overcomes the above-described inadequacies and shortcomings.